I want to create a regular expression for a string of maximum length 12.

The string is following this pattern: ####{value}#####

where # could be $, %, &, * and \n or space. And {value} is a constant string that will always be present. The number of # will vary.

For example

1. ####{value}

2. ###{value}#

3. ##{value}##

4. #{value}###

5. {value}
#### (with newline)

I came up with

/^([\*#$%&\s] {value} [\*#$%&\s]){0, 12}$/

but it's not working.

CodePudding user response：

I would use a positive lookahead to limit the length to a maximum of 12 characters.

^(?!.{13})[*#$%&\s]*. [*#$%&\s]*$

You may sandwich any value you wish between the two character classes of symbols.